The present invention relates to water treatment generally and more particularly to systems and methodologies for biological water treatment.
The following patents and publications are believed to represent the current state of the art:
U.S. Pat. Nos. 3,133,017; 4,045,344; 4,137,171; 4,231,863; 4,256,573; 4,374,730; 4,394,268; 4,521,311; 4,454,038; 4,521,311; 4,566,971; 4,599,174; 4,810,377; 4,820,415; 4,839,053; 5,030,353; 5,200,081; 5,202,027; 5,554,289; 5,698,094; 6,036,863.
French Patent FR 2,707,183.
A NEW PROCESS FOR ENRICHING NITRIFIERS IN ACTIVATED SLUDGE THROUGH SEPARATE HETEROTROPHIC WASTING FROM BIOFILM CARRIERS by Denny S. Parker, Bjorn Rusten, Asgeir Wien and Jon G. Siljudalen, Brown and Caldwell, P.O. Box 8045 Walnut Creek, Calif. 94596-1220, WEFTEC 2000, Copyright 2000 Water Environment Federation;
PILOT STUDY TO FULL SCALE TREATMENT-THE MOVING BED BIOFILM REACTOR EXPERIENCE AT THE PHILLIPS 66 BORGER REFINERY by Chandler H. Johnson and Michael W. Page, WEFTEC 2000, Copyright 2000 Water Environment Federation;
UPGRADING TO NITROGEN REMOVAL WITH THE KMT MOVING BED BIOFILM PROCESS by Bjorn Rusten, Jon G. Siljudalen and Bjornar Nordeidet, Wat. Sci. Tech. Vol 29, No. 12, pp 185-195, 1994;
THE TWO STAGE MOVING BED/ACTIVATED SLUDGE PROCESS, AN EFFECTIVE SOLUTION FOR HIGH STRENGTH WASTES by Narinder Sunner, Chris Evans, Graig Siviter and Tom Bower, Water and Environmental Management, Volume 13, Number 5, October, 1999;
UPGRADING WASTEWATER TREATMENT PLANTS BY THE USE OF BIOFILM CARRIERS, OXYGEN ADDITION AND PRE-TREATMENT IN THE SEWER NETWORK by Anette Aesoy, Hallvard Odegaard, Marius Haegh, Frode Risla and Greta Bentzen, Water Science and Technology, Vol 37, Number 9, 1998.
APPLICATION OF INVERSE FLUIDIZATION IN WASTEWATER TREATMENT: FROM LABORATORY TO FULL-SCALE BIOREACTORS, by D. G. Karamanev and L. N. Nikolov, Environmental Progress, Vol. 15, No. 3, pp 194-196, Fall 1996.
The present invention seeks to provide improved systems and methodologies for biological water treatment.
There is thus provided in accordance with a preferred embodiment of the present invention a method for retrofitting existing waste water treatment facilities having at least one existing basin. The method includes installing generally vertical partitions at spaced locations in at least one existing basin in order to divide the existing basin into a plurality of treatment stage regions, installing at least one air lift in each of the plurality of treatment stage regions, loading each treatment stage regions with a quantity of floatable porous particles, supplying waste water to at least one of the plurality of treatment stage regions and allowing the waste water, but generally not the particles, to flow from at least one of the plurality of treatment stage regions to at least another of the plurality of treatment stage regions and operating the air lift in each of the plurality of treatment stage regions to provide aerobic waste water flow therein in operative engagement with the floatable porous particles.
There is also provided in accordance with a preferred embodiment of the present invention a method for waste water treatment employing at least one basin. The method includes installing generally vertical partitions at spaced locations in at least one basin in order to divide the basin into a plurality of treatment stage regions, installing at least one air lift in each of the plurality of treatment stage regions, loading each treatment stage regions with a quantity of floatable porous particles, supplying waste water to at least one of the plurality of treatment stage regions and allowing the waste water, but generally not the particles, to flow from at least one of the plurality of treatment stage regions to at least another of the plurality of treatment stage regions and operating the air lift in each of the plurality of treatment stage regions to provide aerobic waste water flow therein in operative engagement with the floatable porous particles.
There is further provided in accordance with another preferred embodiment of the present invention a retrofitted waste water treatment apparatus. The apparatus includes at least one existing basin, generally vertical partitions located at spaced locations in the existing basin in order to divide the existing basin into a plurality of treatment stage regions, at least one air lift located in each of the plurality of treatment stage regions and a quantity of floatable porous particles loaded into each of the plurality of treatment stage regions, whereby supplying waste water to at least one of the plurality of treatment stage regions and allowing the waste water, but generally not the particles, to flow from at least one of the plurality of treatment stage regions to at least another of the plurality of treatment stage regions and operating the air lift in each of the plurality of treatment stage regions provides aerobic waste water flow therein in operative engagement with the floatable porous particles.
There is further provided in accordance with yet another preferred embodiment of the present invention a waste water treatment apparatus. The apparatus includes at least one basin, generally vertical partitions located at spaced locations in the basin in order to divide the basin into a plurality of treatment stage regions, at least one air lift located in each of the plurality of treatment stage regions and a quantity of floatable porous particles loaded into each of the plurality of treatment stage regions, whereby supplying waste water to at least one of the plurality of treatment stage regions and allowing the waste water, but generally not the particles, to flow from at least one of the plurality of treatment stage regions to at least another of the plurality of treatment stage regions and operating the air lift in each of the plurality of treatment stage regions provides aerobic waste water flow therein in operative engagement with the floatable porous particles.
Further in accordance with a preferred embodiment of the present invention at least some of the vertical partitions are spaced from a bottom of the basin in order to allow the waste water to flow thereunder between adjacent ones of the plurality of treatment stage regions.
Still further in accordance with a preferred embodiment of the present invention the air lift includes the air diffuser disposed underlying a peripheral enclosure which defines a column of water and is lifted by air diffusing upwardly from the air diffuser therethrough.
Additionally in accordance with a preferred embodiment of the present invention the peripheral enclosure includes a cylindrical enclosure. Alternatively, the peripheral enclosure includes a plurality of spaced generally vertical walls which extend between walls of the basin and are separated from the bottom of the basin.
Further in accordance with a preferred embodiment of the present invention the floatable particles include porous plastic particles having a density lower than that of pure water. Preferably, the particles have a specific gravity between 0.65 and 0.95 and have an irregular shape, whose largest dimension is generally between 4-10 mm.
Additionally in accordance with a preferred embodiment of the present invention, the particles have a total porosity exceeding 50% and have a mean pore diameter of pores, whose diameter exceeds 10 microns, of about 20 microns.
Further in accordance with a preferred embodiment of the present invention the generally vertical partitions divide the basin into between 4 and 12 process stages.
Still further in accordance with a preferred embodiment of the present invention the air lift includes a series of air lifts arranged in the multiple process stages. Preferably, the series of air lifts includes at each process stage an initial air lift assembly and at least one intermediate air lift assembly. The initial air lift assembly typically includes a upstream partition which extends downwardly from a top location above a water level in the basin to a bottom location spaced from the bottom of the basin.
Further in accordance with a preferred embodiment of the present invention the upstream partition extends fully from side to side of the basin.
Additionally or alternatively the upstream partition is attached to a deflector which extends in a downstream direction from the upstream partition at the water level.
Still further in accordance with a preferred embodiment of the present invention the initial air lift assembly also includes a downstream partition which extends fully from side to side of the basin but does not extend up to the water level.
Moreover in accordance with a preferred embodiment of the present invention the intermediate air lift assembly includes an upstream partition which extends downwardly from a top location below the water level in basin to a bottom location spaced from the bottom of the basin.
Further in accordance with a preferred embodiment of the present invention the vertical partitions each extend fully from side to side of the basin.
Additionally in accordance with a preferred embodiment of the present invention the intermediate air lift assembly includes an upstream partition separated from a deflector plate which extends in a downstream direction from the upstream partition at the water level. Preferably, the intermediate air lift assembly also includes a downstream partition which does not extend up to the water level or as close to the bottom of the basin as does the upstream partition.
Still further in accordance with a preferred embodiment of the present invention the step of installing also includes installing a final air lift assembly including an upstream partition which extends downwardly from a top location below the water level in the basin to a bottom location spaced from the bottom of the basin and extends fully from side to side of the basin. Preferably, the final air lift assembly also includes a downstream partition which also extends fully from side to side of the basin and extends to a top location above the water level and closer to the bottom than does the upstream partition. Additionally or alternatively, the downstream partition is attached to a deflector plate which extends in an upstream direction from downstream partition at a location at the water level.
Further in accordance with a preferred embodiment of the present invention the air lift includes a plurality of air lift assemblies each including upstream and downstream partitions: a first plurality of air diffusers are disposed at the bottom of the basin intermediate upstream and downstream partitions of the plurality of air lift assemblies and a second plurality of air diffusers, lesser in number than the first plurality of air diffusers, are disposed at the bottom of the basin intermediate the plurality of air lift assemblies.
Preferably, the first plurality of air diffusers intermediate the upstream and downstream partitions of each air lift assembly causes water to flow upward between the upstream and downstream partitions of each air lift assembly. Additionally, the second plurality of air diffusers intermediate the plurality of air lift assemblies allows water to flow downward.
Still further in accordance with a preferred embodiment of the present invention the step of loading includes loading 10-40 percent of the volume of the basin with particles in absence of water flow.
Additionally in accordance with a preferred embodiment of the present invention the step of supplying includes providing a continuous flow of water from the upstream side of the basin from the waste water inlet to the treated water outlet. Typically, the flow is an undulating flow and includes passage under upstream partitions which is of relatively low volume and generally does not carry floating particles into the air lift, thereby constraining the particles to reside outside of and between the air lift.
Further in accordance with a preferred embodiment of the present invention, the method also includes controlling the flow velocity of water by controlling operation of the first and second pluralities of air diffusers.
Further in accordance with a preferred embodiment of the present invention the air lift includes an adjustable angle deflector.
Still further in accordance with a preferred embodiment of the present invention the air lift includes an integral curved downstream partition and deflector.
Further in accordance with a preferred embodiment of the present invention the method also includes installing a denitrification unit in at least one of the plurality of treatment stage regions. Preferably, the denitrification unit includes a plurality of axial pumps which provide lift generally without an air flow, thereby to provide an anoxic de-nitrification process.
Further in accordance with a preferred embodiment of the present invention the air lift includes an array of air lifts and wherein the array of air lifts includes a multiplicity of cylindrical air lifts arranged in the plurality of treatment stage regions and separated by the vertical partitions which extend from a bottom location and is spaced from a bottom of the basin by a first vertical separation.
Preferably, the cylindrical air lifts each include: a hollow shaft which extends from a bottom location spaced from a bottom of the basin by a second vertical separation which exceeds the first separation, a deflector which is disposed in spaced relationship over each hollow shaft and is disposed at the water level and at least one air diffuser which is disposed underlying each hollow shaft to provide an air lift therethrough, thereby causing water to flow into the hollow shafts and upwardly through the hollow shafts, the deflectors causing the water exiting the tops of the hollow shafts to move sideways and downwardly.
Additionally in accordance with a preferred embodiment of the present invention the cylindrical air lifts also includes a plurality of air diffusers disposed immediately upstream of each the vertical partition for providing control of particle movement and prevention of particle migration.
Further in accordance with a preferred embodiment of the present invention the step of operating produces fluidization of the particles. Preferably, the operating step is operative, when the particles become heavily coated with biomass to cause the particles sometimes to enter the air lift and to be sloughed of some of the biomass as they are propelled upwards by the action of the air lift.